Too much sitting dramatically increases the risk of early death, heart attacks, diabetes and cancer.

A new study says sitting for long periods of time significantly boosts the risk of early death, heart disease, diabetes and cancer — even if you exercise regularly.

The study, published in the Annals of Internal Medicine, shows that people who sit 8 or 9 hours a day have the greatest risk of suffering life-threatening health hazards.

What’s more, scientists said the risk of early death and heart disease isn’t offset by regular exercise.

“Even if you do a half an hour or an hour or of exercise every day doesn’t give us the reassurance that sitting for the other 23 hours is OK,” said study co-author, Dr. David Alter of the Toronto Rehabilitation Institute.

A standup desk can keep you healthier and aid weight loss.

The study shows that sitting for extended periods of time (which most people with desk jobs do every day) increased the risk of cancer by 13%, heart disease by 14% and diabetes by a shocking 91%.

“When you sit, you increase your insulin resistance,” said Dr. Michael Roizen of the Cleveland Clinic. Dr. Roizen co-wrote a series of bestselling weight loss books with Dr. Mehmet Oz, including You: On a Diet.

The average person spends more than half their waking hours working at a computer, sitting in traffic and watching TV. One way to combat the negative health effects of too much sitting is taking 1 to 3-minute breaks every half hour throughout the day.

This can also aid weight loss, since standing burns almost twice as many calories as sitting.

Another way to prevent sitting-induced early death, cancer and diabetes is to use a stand up desk, which some offices have introduced to keep their employees healthy.

Celebrities who use standing desks include talk show host Jimmy Kimmel, who installed a treadmill desk in his office in 2012.

“I read somewhere that sitting all day can cut 15 or 20 years off your life,” Kimmel told TV Guide. “It’s worse than smoking.”

“Today Show” weatherman Al Roker also uses a treadmill desk. Roker, who lost 165 pounds after getting gastric bypass surgery, said his standing desk helps him maintain his weight loss.